This invention relates generally to clocks and timers, and in particular to timing devices for use in the educational classroom.
Timing devices, and particularly electronic timing devices, are well known in several fields. However, typical timing devices, especially those which function predominantly in stop watch mode, have small displays, not readily viewed by a large number of people in a classroom type setting. While large clocks have been standard in classrooms for some time, these clocks typically do not function as timers or stop watches. Large display timers are available, as for sporting events, but generally are too costly to be provided in every school classroom, especially where such an item is not the subject of daily use in the classroom.
A projecting alarm clock has previously been marketed which projects a digital time readout upwardly, onto the ceiling of a room. The image projected is dim, suitable for use only in a darkened room. Intended for bedroom use, the clock allows a user merely to look at the ceiling to see the time, without rolling over in bed to read a clock. The projectable alarm clock has a built-in light source for projection, seemingly not employing an LCD for projection. Instead, the clock apparently uses a mechanical template to project lighted numerical images. It is believed limited to a fixed narrow focus range corresponding to approximately six or seven feet. As compared to the purposes and functions of the present invention, the projecting alarm clock lacks several features, including not functioning as a stop watch or timer and not being compatible with an overhead projector. Additionally, the clock is relatively bulky and mechanically complex.
Overhead projectors are commonly used in classrooms for displaying information to a classroom. Such overhead projectors are commonplace in most schools, serving as standard equipment. The vast majority of teachers in the United States are familiar with overhead projectors, and frequently use them in class demonstrations.
While overhead projectors are typically used for viewing transparencies, other devices have been designed for overhead projector use. Calculators have been designed for overhead projector use, whereby the calculator has a transparent liquid crystal display so that when the calculator is placed on an overhead projector the LCD display is projected onto a wall or screen. See Judd U.S. Pat. No. 4,154,007. In some overhead projector calculators the keyboard section is also transparent, facilitating classroom demonstrations of the use of the calculator. See, for example, Stokes U.S. Pat. No. 5,035,502. Such overhead projectable calculators take advantage of the wide availability of overhead projectors.
There is a need for a timing device which is inexpensive, small and portable, and capable of producing a large scale display visible to an entire classroom. Accordingly, it is an object of the present invention to provide a timing device adapted so its timing read-out can be readily projected for group viewing with an overhead projector. A further object is to provide a timing device which is rugged, designed to withstand dropping and heat, and versatile in being useful in a secondary mode as a desk top clock or timer.